This puzzle:

Joe Krozel notes: It's hard for me to pick out a favorite puzzle, but this
one is probably in my top five. This is the puzzle one
should pull out when challenging anyone who claims
he/she can solve a puzzle with only the Across clues.

This puzzle exists thanks to the clue database
which Matt Ginsberg provided to the crossword
community. The database has a nice feature of
displaying all other entries — of the same length
as the word being queried — having an identical
clue. So, for instance, if I type TABLE into the
database I find that it and two other words —
DEFER and DELAY — have been clued as
[Put on hold]. So, when I saw this feature for
the first time, I immediately conceived of the
current puzzle concept. From there I just
frantically hunted down all the 7-letter entries
which shared a common clue.